TM 5-4240-501-14&P
STARTERS
Gear Drive 12V & 120V
Insert the tachometer in the end of the starter motor
shaft and activate the starter motor. A starter motor in
good condition will be within the following specifications.
1.
Starter motor RPM - 5,600 minimum.
2.
Current - 6 amperes maximum (disregard surge
current)
CHECKING THE 120 VOLT AC
STARTER MOTOR
A performance test of the 120 volt starter motor may be
made in the following manner.
Equipment Needed -
1.
A tachometer capable of reading 10,000 RPM.
2.
An ammeter capable of reading 0 to 10 amperes
AC (RMS).
DANGER: The performance test of this starter requires
the use of an ammeter, connected in the 120 volt AC
starter motor circuit. Extreme care should be used in
making this test to minimize the hazard of electrical
shock.
Clamp the starter motor in a vise as shown. An ammeter
may be connected as shown in the accompanying
illustration. Fig. 73. Plug the electrical cord into a 120
volt outlet and insert the tachometer in the end of the
starter motor shaft.
CAUTION: Starter motor housing contains two powerful
ceramic magnets that may crack if motor housing is
clamped in a vise or struck with a hammer or a hard
object.
Fig. 73 - Checking 120 Volt Starter Motoi
Performance
A starter motor in good condition will be within the
following specifications.
1.
Starter Motor RPM - 8,300 minimum.
2.
Current -- 1/2 amperes maximum AC.
If either the 120 volt AC or 12 volt DC starter motor does
not perform satisfactorily, the following should be
checked and corrected if necessary.
1.
Binding condition between the pinion gear, helix
and drive gear assembly.
2.
Misalignment or binding between motor bearings.
3.
Starter motor brushes sticking in brush holders.
4.
Dirty or worn commutator.
5.
Shorted, open or grounded armature.
A. Shorted armature (wire insulation worn and wires
touching one another) will be indicated by slow
speed and high current.
B. Open armature (wire broken) will be indicated by
low or no RPM.
C. Grounded armature (wire insulation worn and
wire touching armature lamination or shaft) will
be indicated by excessive current or no RPM.
6.
A defective starter motor switch (in cord).
7.
A defective starter motor rectifier assembly.
8.
Weakened magnets.
DISASSEMBLY OF STARTER MOTOR
Study Fig. 69 prior to starter motor disassembly.
NOTE: END HEAD, END CAP AND HOUSING MUST
BE PLACED IN THE SAME POSITION AS WHEN
REMOVED, OR INTERFERENCE MAY RESULT. See
Fig. 74.
Fig. 74 - Match Marks
Remove thru bolts. Fig. 75. The end cap may then be
removed.
(See checking starter motor drive if repair, cleaning or
replacement of drive assembly is necessary.)
20
